The present invention generally relates to aircraft antennas and more particularly to an antenna component that is a structural member of the aircraft.
Modern aircraft have a need to provide radio communication over a variety of frequency ranges and communication modes. For example, radio communication may be in the VHF band using amplitude modulation (AM) and/or frequency modulation (FM) or in the UHF band. In order to communicate effectively, the aircraft must include multiple antennas dispersed on the aircraft. Typically, the aircraft will include antennas mounted behind a radio transparent skin of the aircraft, and/or exterior blade antennas mounted to the skin of the aircraft.
For effective communication, the antenna dimensions should be in the same order of magnitude as the wavelength of the signal being propagated. In this respect, the wavelength for operation in the VHF/FM band (i.e., 30-88 MHz) is approximately 3-10 meters. Accordingly, for effective communication within this band range, the antenna must have a size correspondingly large. However, this is not practical because an antenna of this size would be aerodynamically inefficient. Therefore, small blade antennas electrically matched through impedance tuning networks are used. The blade antenna is a small fin protruding from the skin of the aircraft that is used as the radiating element.
Blade antennas are aerodynamically inefficient because they protrude from the skin of the aircraft. Typically, multiple blade antennas are used on the aircraft for the multiple communications bands (i.e., UHF, VHF/FM, VHF/AM). The blade antenna exhibits poor performance characteristics at lower frequencies (i.e., 30-88 MHz). The blade antenna is constructed to withstand the forces subjected to the antenna, however the blade antenna is still susceptible to impact damage (i.e., break off). The blade antenna does not add any structural strength to the aircraft, and interferes with the aerodynamic efficiency of the aircraft.
The present invention addresses the above-mentioned deficiencies in prior aircraft antenna design by providing an antenna that is a structural member of the aircraft. In this respect, the aircraft antenna of the present invention is a structural member of the aircraft tail that electrically couples the skin of the tail to the antenna in order to provide a radiating element. Accordingly, the tail member of the aircraft becomes the antenna radiating element.